Does Keto Help or Hurt Your Liver? The Case of Keto and NAFLD

There’s no doubt keto is controversial. A diet that involves getting up to 80% of your calories from fat is bound to raise eyebrows and have your doctor nod in disapproval. But a lot of this controversy is really only based on dietary dogma. When you look at the actual science is when you see that keto (the ketogenic diet) is one with lots of potentials.

Recently, one of the latest controversial claims about keto is that it is bad for your liver. More specifically, it is said to cause non-alcoholic fatty liver disease (NAFLD), a condition that affects 20–30% of people in the Western world [1]. But most studies examining keto and its effects on the liver show the exact opposite — that it reverses NAFLD and can even prevent its onset.

Which begs the question: how can that be true when keto is a high-fat diet and doctors frequently recommend lowering fat intake when tackling this common liver problem? Keep reading to find out.

Why Some People Get NAFLD

Chronic heavy drinking and medication overuse are known causes of fatty liver and other liver problems. However, NAFLD refers to something else: a broad spectrum of conditions characterized by fat buildup in the liver in people who don’t drink too much. That’s why doctors need to rule out alcohol abuse, as well as chronic use of medications and certain hereditary disorders, before making a diagnosis of NAFLD.

Like many other conditions, NAFLD can be mild or severe. In mild cases, a biopsy will show that 10% of hepatocytes (liver cells) have fat droplets [2]. In severe cases, there will also be scarring, inflammation, or even cirrhosis. Luckily, only 25% of NAFLD cases end up becoming severe [3].

But what exactly causes NAFLD?

There’s no definite answer to that. But what experts know is that the condition is more common in people with [2, 3]:

• Overweight or obesity
• Type 2 diabetes
• Elevated triglycerides
• Metabolic syndrome

Insulin resistance seems to be the main driver behind NAFLD, which is why experts call this condition “the hepatic manifestation of the metabolic syndrome [4].” This makes perfect sense considering the condition is steadily becoming more prevalent alongside obesity, diabetes, and other metabolic problems.

But then again, why would insulin resistance lead to fat buildup in the liver?

Liver fats can form from three things: the breakdown of fat in fat tissue, production of fat in the liver itself, or from fat in food. But according to one review, a significant contributor to fat buildup in the liver is when insulin resistance causes carbs to turn to fat in the liver[5].

Insulin resistance is a metabolic condition in which your cells don’t respond to insulin as they should. This causes high blood sugar, which the body handles by diverting all that blood glucose to the liver.

Animal studies also show that deficiencies in two essential nutrients, choline and metathione, can lie behind NAFLD [5]. Both are found in eggs, fish, nuts, and seeds, and they’re essential for health.

How to Tell if Your Have NAFLD

NAFLD won’t cause symptoms in most people, so there’s no way to tell other than through an ultrasound or CT scan.

Your doctor may have your liver checked if routine tests point to a liver problem. For example, if a blood test shows increased levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), which are liver enzymes.

If NAFLD progresses to non-alcoholic steatohepatitis (inflammation of the liver), fibrosis (scarring of the liver), or cirrhosis (scarring and shrinking of the liver), then you will develop symptoms. The most common symptoms of liver problems include [6]:

• Dull pain in the top right of your abdomen
• Being very tired
• Unintentional weight loss
• Feeling weak
• Yellow skin and eyes
• Itchy skin
• Swollen legs, ankles, and feet
• Abdominal swelling

If you are overweight, especially around your tummy area; having type 2 diabetes; have high triglycerides, metabolic syndrome, and you are inactive, you may be at risk of fatty liver. Luckily, you can reduce this risk by changing what you eat and exercising.

Can Following a Keto Diet Cause NAFLD?

In short, no.

There is no evidence that a keto diet inevitably leads to fatty liver, despite it being notoriously high in fat. In fact, a recently published comprehensive review on the subject concluded that virtually all studies found that low-carb and keto diets led to improvements in liver fat content [7].

The same review commented on an experiment:

“The common belief that increasing dietary fat intake invariably leads to fatty liver and prevents fat mass loss has been recently proven wrong.”

So, although it might seem logical that eating more fat makes you and your liver fat, our bodies are much more complex than that. As already said, evidence shows that too many carbs in our diets are the likely culprits of NAFLD by causing insulin resistance. But it’s not so much the amount of carbs as the type that seems to be the problem.

When most of your carbs are simple glucose or fructose as opposed to starch and fiber, you’re more likely to develop insulin resistance and NAFLD [5, 8]. Fructose is a simple fruit sugar that does not raise blood glucose. Instead, it goes straight to the liver where it is converted into fat when eaten in excess. Excess glucose can do the same.

When it comes to fat intake, though, eating too much of it can be just as bad [8]. That’s simply because too much of any macronutrient leads to weight gain, and weight gain leads to insulin resistance. When it comes to the type of fat that’s worse for liver health, saturated fat is problematic, while unsaturated fats improve metabolic and liver health.

And What About All That Fat on Keto?

That’s where things become paradoxical. To understand why that’s the case, you need to know how the keto diet affects a person’s metabolism:

On a keto diet, carb intake is so low that it cannot fuel the cells properly. As a result, the body switches to burning fat for fuel. In the process, the liver converts some of this fat (from food and fat cells) into molecules called ketones. These molecules replace glucose as fuel in the brain, heart, and other tissue and you’re officially in a metabolic state called ketosis.

For all of this to happen, you should be eating more fat and less carbs.

And once you reach ketosis, you can expect a host of metabolic benefits. For example, ketosis lowers insulin levels and improves insulin sensitivity [9]. With lower insulin comes increased fat burning and weight loss. Thirdly, you eat fewer carbs on a keto diet so less end up in the liver to be converted into fat. With all of this comes the reversal of metabolic syndrome.

But to follow keto properly, you need to eat more fat than you’re used to. The typical macronutrient distribution on a keto diet is 5–10% calories from carbs, 15–30% from protein, and 60–75% from fat. On a 2,000-calorie diet, that’s 133–166g of fat per day, while it’s normally recommended to eat around 60g.

However, you’ll likely be eating even less than that since keto is known to suppress appetite [9]. And besides, you’ll need to be in a calorie deficit even on this diet to lose weight.

Of course, some studies link low-carb and keto diets to the development of NAFLD; however, these are usually animal studies or low-quality ones. For example, there’s a recently published case study of a woman developing elevated liver enzymes after going keto, which the researchers believe puts her at risk of NAFLD [10]. But this is an isolated case and the woman in question was physically inactive and was taking multiple medications.

So Should I Follow Keto to Beat NAFLD?

As a word of warning: always speak to your doctor when tackling any medical issue with diet and lifestyle modifications!

With that said, your doctor likely already recommended certain diet and lifestyle modifications to help you reverse NAFLD. What’s typically suggested is [11, 12]:

• Weight loss if you’re overweight
• Regular exercising
• Drinking coffee
• Taking vitamin E supplements

Since the keto diet can help with some of the above, you can consider it if you’re willing to follow it long enough.

The keto diet is a great weight-loss option if you’re willing to limit carbs, get most of your calories from fat, and track your nutrient intake day in, day out. However, any diet that helps people lose weight is good enough for treating NAFLD as long as it’s not a starvation diet and too high in carbohydrates.

And when shouldn’t you follow keto to treat NAFLD?

The keto diet isn’t always safe [13]. If you have any of the following, don’t start a keto diet:

• Pancreatitis
• Liver failure
• A Fat metabolism disorder
• Carnitine deficiency disorders
• Pyruvate kinase deficiency
• Porphyria

Keto may also not be safe for pregnant and breastfeeding women, and people with type 1 diabetes need to be especially cautious about adjusting their medication on this diet.

Conclusion

While it may seem counterintuitive, keto can reverse fatty liver, not cause it. This is backed up by a body of research now covered in multiple study reviews and meta-analysis.

NAFLD is often a result of a poor diet and a sedentary lifestyle. Luckily, it’s easy to reverse it with healthy eating and exercising, and keto can help. Keto works against NAFLD by lowering insulin, promoting weight loss, and helping you eat fewer carbohydrates. Of course, there are many other mechanisms of action behind keto’s magic not discussed here.

If you’re interested in starting this diet, do talk to your doctor first. They can help you stay safe on this diet and monitor your progress if you already have NAFLD.

References:

1. Milić S, Stimac D. Nonalcoholic fatty liver disease/steatohepatitis: epidemiology, pathogenesis, clinical presentation and treatment. Dig Dis. 2012;30(2):158–62. — https://www.karger.com/Article/Abstract/336669
2. Kudaravalli P, John S. Nonalcoholic Fatty Liver. Treasure Island (FL): StatPearls Publishing; 2020 Jan- https://www.ncbi.nlm.nih.gov/books/NBK541033/
3. Perumpail BJ, Khan MA, Yoo ER, Cholankeril G, Kim D4, Ahmed A. Clinical epidemiology and disease burden of nonalcoholic fatty liver disease. World J Gastroenterol. 2017 Dec 21; 23(47): 8263–8276. — https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5743497/
4. Vanni E, Bugianesi E, Kotronen A, De Minicis S, Yki-Järvinen H, Svegliati-Baroni G.From the metabolic syndrome to NAFLD or vice versa? Dig Liver Dis. 2010 May;42(5):320–30. — https://www.ncbi.nlm.nih.gov/pubmed/20207596
5. Schugar RC, Crawford PA. Low-carbohydrate ketogenic diets, glucose homeostasis, and nonalcoholic fatty liver disease. Curr Opin Clin Nutr Metab Care. 2012 Jul;15(4):374–80. — https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3679496/
6. NHS. Non-alcoholic fatty liver disease (NAFLD). 2018 Nov — https://www.nhs.uk/conditions/non-alcoholic-fatty-liver-disease/
7. Watanabe M, Tozzi R, Risi R, et. al. Beneficial effects of the ketogenic diet on nonalcoholic fatty liver disease: A comprehensive review of the literature. Obes Rev. 2020 Mar 24. — https://onlinelibrary.wiley.com/doi/full/10.1111/obr.13024
8. Ullah R, Rauf N, Nabi G, et. al. Role of Nutrition in the Pathogenesis and Prevention of Non-alcoholic Fatty Liver Disease: Recent Updates. Int J Biol Sci. 2019; 15(2): 265–276. — https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6367556/
9. Gershuni VM, Yan SL, Medici V. Nutritional Ketosis for Weight Management and Reversal of Metabolic Syndrome. Curr Nutr Rep. 2018 Sep; 7(3): 97–106. — https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6472268/
10. Anekwe CV, Chandrasekaran P, Stanford FC. Ketogenic Diet-induced Elevated Cholesterol, Elevated Liver Enzymes and Potential Non-alcoholic Fatty Liver Disease. Cureus. 2020 Jan; 12(1): e6605. — https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7008768/
11. American Liver Foundation. What are the treatments for NAFLD and NASH? Accessed 2020 Apr. — https://liverfoundation.org/for-patients/about-the-liver/diseases-of-the-liver/nonalcoholic-steatohepatitis-information-center/nash-treatment/
12. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Treatment for NAFLD & NASH. How do doctors treat NAFLD and NASH? 2016 Nov. — https://www.niddk.nih.gov/health-information/liver-disease/nafld-nash/treatment
13. Masood W, Annamaraju P, R. Uppaluri K. Ketogenic Diet. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK499830/